What type of airspace is controlled by a facility other than an airport?

The correct answer is that restricted airspace is controlled by a facility other than an airport. Restricted airspace is designated for specific purposes, such as military operations or sensitive activities, and access is limited to authorized aircraft only. The controlling agency, which is usually a military institution or government entity, manages this airspace to ensure safety and security during operations.

Controlled airspace refers to airspace where air traffic control (ATC) provides air traffic service and is typically associated with airports, while public airspace is more general and does not specify control requirements by specific facilities. Open airspace doesn't have the intricate control structures that restricted or controlled airspace has. In contrast, restricted airspace enforces strict regulations, making it distinct from other types of airspace controlled by various entities.